Peppermint and ice cubes convey the chill, and campfires and sunshine deliver warmth. Being bitten, scalded, punched, stabbed, etc. will all trigger a common reaction, that is: pain! Inflamed appendix, stomach pain; heart attack, chest pain; brain tumor, head pain; toothache, body pain… But what exactly is pain?
Some people say: “Pain is not a disease, it can kill people when it hurts.” Others say that pain is a subjective feeling. As early as 1968, pain expert Margo McCaffery first proposed a commonly used definition: “When a person says he feels pain, it is pain; he says pain is still there, and pain is still there.” So I am.”
Medically speaking, pain, unlike other sensations, is an unpleasant complex of sensations associated with injury and suffering, a complex psychophysiological activity. Pain varies in intensity (mild, moderate, severe), nature (sharp, dull, or burning), duration (instantaneous, short-term, persistent), and localization (surface, deep tissue, well-localized, or diffuse). There is great variability and, therefore, it is difficult to give a satisfactory clear definition of pain. In 1994, the International Society for the Study of Pain defined pain as: “an unpleasant subjective sensory and emotional experience associated with tissue damage or potential damage.”
Under normal physiological conditions, pain provides an alarm signal of physical threat and is not A missing life-saving feature. However, under pathological conditions, pain is a common symptom of most diseases, often intertwined with autonomic nerve activity, motor reflexes, psychological and emotional responses, causing pain to patients. In fact, chronic pain is not only a symptom, it is also a disease itself, which is a major clinical problem. Therefore, the World Pain Congress listed pain as the fifth vital sign after breathing, pulse, blood pressure and body temperature, and designated October 11 every year as “World Pain Relief Day”.
The biggest difference from other somatosensory sensations is that pain sensation cannot or is extremely difficult for people to adapt to, and it contains both “sensation” and “emotion” components. The “sense” component has a common feature of other senses: there are special receptors. Activation of receptors requires appropriate stimulation, localization distribution, and the ability to identify stimulus intensity. The “emotional” component of pain perception is closely related to escape responses, is highly variable, and is highly susceptible to past experience. For example, depression, loneliness, and sadness are more likely to aggravate pain, while placebos, hypnosis, suggestion, and optimism can reduce pain. A large number of studies have shown that pain is not simply related to changes in a certain part of the body, nor can it be considered to be transmitted by a single conduction bundle, nerve nucleus and neurotransmitter in the nervous system, it is a complex sensory system.
where does the pain come from
Pain comes from receptors, and our skin and mucous membranes are covered with receptors. These receptors transmit external stimuli to the brain through neural pathways, and the brain sends out instructions: Area X now feels pain!
The receptors also have their own division of labor. For example, when the temperature rises to a certain level, the capsaicin receptor protein TRPV1 is activated; when the stress reaches a certain level, the mechanosensitive ion channel Piezo is activated; cold stimulation activates the TRPM8 receptor, which causes cold sensation.
Pain receptors are sensitive to noxious stimuli; touch and pressure receptors receive mechanical stimuli; cold and heat receptors respond to temperature stimuli. These receptors do not interfere with each other and perform their respective functions. Therefore, we can feel pain at the same time as feeling hot, or feel pain at the same time as being bumped, and there is no precedence.
Pain receptors send stimuli of various natures that may or have caused damage to neural pathways, and finally let the brain send pain commands, accompanied by strong emotional responses (sad, pain, etc.), to deepen the “lessons” of pain to the body.
According to the different pathogenesis, pain can be divided into two categories: one is the pain caused by the direct excitation of nociceptors by nociceptive stimuli under physiological conditions, which is called “nociceptive pain”; the other is caused by inflammatory stimulation Pain caused by , nerve damage and abnormal nerve function is called “pathological pain”.
Under normal physiological conditions, the activation of nociceptors is the basis for pain perception. Nociceptors transmit afferent electrical impulses through the spinal cord to the brain, where they are processed in the higher centers of the brain, ultimately producing pain sensation. The nerve fibers that perform this task are primarily unmyelinated class C primary afferent fibers (mainly conducting cautery) and myelinated Aδ class primary afferent fibers (mainly conducting sting). A single impulse and low-frequency firing of a receptor do not cause pain, and pain can only be produced by simultaneously activating many Aδ or C nociceptors, and the firing frequency of the two is proportional to the intensity of pain perception.
However, in pathological conditions, the mechanism of pain caused by nerve injury and tissue inflammation is more complex, including not only the activity of nociceptors, but also the activation of non-nociceptors. Nociceptive stimuli cause the injured tissue to release pain-causing chemicals. These chemical pain-causing factors are secreted or released by cells and bind to the corresponding receptors to activate nociceptors or enhance their excitability, making people more susceptible to pain. Pain is easily felt. Such as K+, H+, histamine, Ach (acetylcholine), 5-HT (serotonin), ATP (adenosine triphosphate), prostaglandins and leukotrienes, as well as neuropeptides substance P, etc., are all pro-inflammatory factors that cause pain .
Smiling can reduce pain
Pain, as a warning of the body being injured, can trigger a series of defensive protective responses in the body, making people act urgently, avoid danger and harm the body, and protect the body. But some long-term severe pain is an unbearable torture for life. Especially cancer pain, once it occurs, people are often approaching the end of their lives, which is sighing. Even mild to moderate pain brings endless trouble to life. As the saying goes, “Toothache is not a disease, it can kill you when it hurts” is a true portrayal. And “splitting headache” (referring to headache), “jumping up and down, rolling on the floor” (often a manifestation of a ureteral stone attack), “heart like a knife” (mostly a manifestation of a heart attack), etc. are severe pain and vivid ‘s portrait. What a joy in life to relieve or get rid of pain.
It can be said that every progress in the study of the theoretical mechanism of pain has brought new hope to the prevention and treatment of pain. Any measure that reduces afferent impulses to nociceptors can help to treat or relieve pain, such as traditionally used local anesthetics to block nerve afferents, acupuncture, and mild electrical stimulation of nerves, as well as the most basic analgesic drugs. use etc. Psychotherapy has also been widely used in analgesia treatment based on the influence of psychological factors on the generation and prevention of pain.
According to a report published in Scientific American, laughter may be the best pain reliever. As we all know, laughter has many benefits, such as “smile, ten years less”. In addition, laughter can increase lung capacity, speed up blood circulation, and even a panacea for pain relief.
This is because laughing a lot releases chemicals called endorphins that make the brain feel good. Endorphins are usually produced during exercise, excitement, eating spicy food, falling in love, etc. A series of deep breathing exercises accompanied by laughter can cause physiological fatigue of abdominal muscles, which will also stimulate the production of endorphins in the body, thereby The ability of the body to endure pain is greatly improved. In a related trial, subjects who watched a 15-minute humorous video clip of “Mr Bean” or “Friends” had around 10 percent better ability to tolerate pain; if the content wasn’t funny, the ability to tolerate pain increased reduce.
Of course, there are still many unsolved mysteries about pain that haunt you and me. We hope that with the advancement of technology, we can reveal the mysteries of pain one by one and get rid of the entanglement of pain.
The World Health Organization (WHO) classifies pain levels as:
O degree: no pain;
I degree: mild pain, intermittent pain, no medication;
II degree: moderate pain, continuous pain, affecting rest, need analgesics;
III degree: severe pain, continuous pain, no use Medicine can not relieve pain;
IV degree: severe pain, continuous severe pain with changes in blood pressure and pulse.